| Water | 17.24 | |
| Organic matter* | 9.64 | |
| Oxide of iron and alumina | 11.89 | |
| Carbonate of lime | 14.50 | |
| Magnesia, alkalies, etc. | 1.53 | |
| Insoluble silicious matter | 45.20 | |
| 100.00 | ||
| 2d determination. | ||
| * Containing nitrogen | .306 | .380 |
| Equal to ammonia | .370 | .470 |
“Both portions of the clover-soil thus contained about the same percentage of organic matter, and yielded nearly the same amount of nitrogen.
“In addition, however, to the nitrogen in the clover-roots, a good deal of nitrogen, in the shape of root-fibres, decayed leaves, and similar organic matters, was disseminated throughout the fine soil in which it occurred, and from which it could not be separated; but unfortunately, I neglected to weigh the soil from a square yard, and am, therefore, unable to state how much nitrogen per acre was present in the shape of small root-fibres and other organic matters.
“Before mentioning the details of the experiments made in the next season, I will here give the composition of the ash of the partially cleaned clover-roots:
| Oxide of iron and alumina | 11.73 |
| Lime | 18.49 |
| Magnesia | 3.03 |
| Potash | 6.88 |
| Soda | 1.93 |
| Phosphoric acid | 3.61 |
| Sulphuric acid | 2.24 |
| Soluble silica | 19.01 |
| Insoluble silicious matter | 24.83 |
| Carbonic acid, chlorine, and loss | 8.25 |
| 100.00 |
“This ash was obtained from clover-roots, which yielded, when perfectly dry, in round numbers, eight per cent of ash. Clover-roots, washed quite clean, and separated from all soil, yield about five per cent of ash; but it is extremely difficult to clean a large quantity of fibrous roots from all dirt, and the preceding analysis distinctly shows, that the ash of the clover-roots, analyzed by me, was mechanically mixed with a good deal of fine soil, for oxide of iron, and alumina, and insoluble silicious matter in any quantity, are not normal constituents of plant-ashes. Making allowance for soil contamination, the ash of clover-roots, it will be noticed, contains much lime and potash, as well as an appreciable amount of phosphoric and sulphuric acid. On the decay of the clover-roots, these and other mineral fertilizing matters are left in the surface-soil in a readily available condition, and in considerable proportions, when the clover stands well. Although a crop of clover removes much mineral matter from the soil, it must be borne in mind, that its roots extract from the land, soluble mineral fertilizing matters, which, on the decay of the roots, remain in the land in a prepared and more readily available form, than that in which they originally occur. The benefits arising to wheat, from the growth of clover, may thus be due partly to this preparation and concentration of mineral food in the surface-soil.
“The clover on the hillside field, on the whole, turned out a very good crop; and, as the plant stood the winter well, and this field was left another season in clover, without being plowed up, I availed myself of the opportunity of making, during the following season, a number of experiments similar to those of the preceding year. This time, however, I selected for examination, a square yard of soil, from a spot on the brow of the hill, where the clover was thin, and the soil itself stony at a depth of four inches; and another plot of one square yard at the bottom of the hill, from a place where the clover was stronger than that on the brow of the hill, and the soil at a depth of six inches contained no large stones.
SOIL NO. 1. (CLOVER THIN), ON THE BROW OF THE HILL.
“The roots in a square yard, six inches deep, when picked out by hand, and cleaned as much as possible, weighed, in their natural state, 2 lbs. 11 oz.; and when dried on the top of a water-bath, for the purpose of getting them brittle and fit for reduction into fine powder, 1 lb. 12 oz. 31 grains. In this state they were submitted as before to analysis, when they yielded in 100 parts:
| Moisture | 4.34 |
| Organic matter* | 26.53 |
| Mineral matter | 69.13 |
| 100.00 | |
| * Containing nitrogen | .816 |
| Equal to ammonia | .991 |